Method of unloading large containers

ABSTRACT

A method for unloading a plurality of roll-off containers from a special trailer is disclosed. A plurality of six roll-off containers are stacked to form two similar nests of at least two containers each, with the lowermost container of each nest oriented in horizontal alignment and having its bottom rail resting upon the rollers of the trailer. The two nests of containers are placed upon the trailer in longitudinal juxtaposition for transportation purposes. Upon reaching the destination, the two nests of containers are unloaded by a single driver without requiring any external, additional equipment. During unloading, the trailer is backed and suddenly stopped in repeated stages to employ inertial forces to move the nests of containers relative to the trailer until the nests of containers travel the length of the trailer and drop upon the ground.

This is a division, of application Ser. No. 468,319, filed Feb. 22,1983, now U.S. Pat. No. 4,599,040.

FIELD OF INVENTION

This invention relates generally to the field of highway transporationequipment, and more particularly, is directed to a method and apparatusfor transporting large trash containers from the place of manufacture tothe premises of the ultimate user.

BACKGROUND OF THE INVENTION

The use of large roll-off trash containers in and about buildingconstruction sites, commercial establishments and certain industriallocations is well known and such large containers are popularly employedas local points of disposal for all kinds waste and other materialswhich are intended to be discarded. It is usual to both place and removesuch large containers when filled or when empty by employing speciallydesigned hoists. The hoists are cooperatively designed for use with thelarge trash containers whereby such containers can easily betransported, either when loaded or empty, as necessary to satisfy thelocal conditions of use.

The large roll-off trash containers are usually constructed ofstandardized dimensions to provide the desired capacity, which capacityis generally designated in cubic yards. The containers are designed withbottom rails suitable for cooperative rolling engagement on eitherinside or outside roller systems which are substantially uniformlyemployed on the hoists of various manufacturers. The roll-off containersare characterized by sturdy, welded steel construction with an open top,a steel floor to which the bottom rails are affixed and enclosing sidewalls. The rear side wall is usually a door which is pivotally securedto the remainder of the side wall construction in a hingedinterconnection to provide a rear, horizontally openable door. One ofthe most common trash container sizes has a capacity of 30 cubic yards,is 22 feet in length, 8 feet in width and has side walls which are 62inches high. Typically, the side wall construction comprises 11 gaugeplate sides and 11 gauge steel tubes of 3 inch by 5 inch dimensionsspaced 24 inches on center. The floor is usually 3/16 inch steel platewith bottom affixed 3 inch channel cross sills and 2 inch by 6 inchrails. The doors are usually fabricated similarly to the side walls.

After the large containers are fabricated at the factory, they arepainted and prepared for delivery to the customer. It is now the commonpractice to utilze a trailer to haul a plurality of completed trashcontainers to the place of intended use. Keeping in mind the usualinterstate trucking regulations, the overall length of a tractor andtrailer must be limited, usually to 60 feet overall length with astandard maximum width of 102 inches. Maximum overall height isgenerally limited to 13 feet, 6 inches.

With the above dimensional limitations in effect, in the past and upuntil the present invention, it was the common practice to employ aflatbed trailer for transportation of the large roll-off containers. Thetrailers were constructed of suitable length to support and transporttwo trash containers in end-to-end juxtaposition. Usually, a trailer 45feet in length was found to be adequate for this purpose. In order tomake the most economic use of the 45 foot trailer, the prior workers inthe art usually shipped four trash containers per trailer by nesting twopairs of containers. This was accomplished, by turning the trashcontainers on their sides and by interleaving one pair of trashcontainers at the front half of the trailer and one pair of trashcontainers at the rear half of the trailer. By so loading the trailer,the highway regulations regarding overall length, width and heigth ofthe loaded trailer could be rather easily complied with. It will beappreciated however that upon consideration the total value of the trashcontainers and further considering the costs in transporting such largeand bulky articles over a highway, the delivery costs involvedconstitute a significant factor in the overall costs of each container.This transportation cost must be calculated and included in the totalcontainer cost to be recovered at the time the container was sold. Inview of the relatively high cost of delivery when considering the natureand cost of the article itself, the prior workers in this field havebeen seeking improved methods and apparatus for delivery of the finishedtrash containers at reduced overall costs.

SUMMARY OF THE INVENTION

The present invention relates generally to the field of large trashcontainers, and more particularly, is directed to an improved method andapparatus for simultaneously carrying a plurality of large roll-offcontainers over interstate highways for delivery to the point of use.

The method and apparatus of the present invention contemplates the useof a novel structural steel trailer that employs a pair oflongitudinally aligned, transversely spaced main rails for support ofthe trash containers in a manner which completely eliminates the usualflat bed construction of the presently available trailers. The mainrails are designed and dimensioned to simulate the construction ofconventional hoists of the type which employ either or both inside andoutside rollers. The usual inside-outside roller type hoist is equippedwith a plurality of longitudinally spaced outside rollers and left andright longitudinal divider bars for supporting a plurality oflongitudinally spaced inner rollers. In this manner, the trailer of thepresent invention can be utilized substantially universally to transporttrash containers which are designed for use with all popularly employedhoist systems.

The method of the present invention contemplates nesting a firstplurality of three large roll-off containers on the forward half of thetrailer and a second plurality of three large roll-off containers on therearward half of the trailer in a manner to permit a single trailer tobe employed to transport trash containers, six at a time. The loadingpermits transportation over interstate highways in a manner whichcomplies with all known length, height and width regulations. Byemploying the method and apparatus of the present invention, six largetrash containers now can simulataneously be transported by a singletractor trailer apparatus in lieu of the former limit of only four trashcontainers per tractor trailer unit. By employing the method andapparatus of the present invention, the transportation costs fordelivery of completed large roll-off containers can thereby be reducedby a factor of substantially fifty percent.

In order to accomplish the significant reduction in transportationcosts, the front and rear nests of roll-off containers are each arrangedwith the bottom, or lowermost container in usual, up-right orientationwherein the bottom positioned rails can be applied over the trailerinside or outside rollers in the same manner that the rails weredesigned for employment with the hoist rollers on the job site.Accordingly, the trailer inside or outside rollers will support eachlowermost front and rear trash container in a manner to permit rollingengagement of the trash containers on the trailer.

The second and third roll-off containers of each nest are oriented ontheir respective sides and are interleaved and placed within thesidewalls of the lowermost containers. In this manner, three roll-offcontainers will be interleaved and nested on the forward portion of thetrailer and a similar arrangement of three roll-off containers will bepositioned on the rearward portion of the trailer. It is noteworthy thatby constructing the trailer with main rails and inside and outsiderollers in place of the former flatbed trailer construction, theover-all height of the trailer and roll-off container nest combinationcan be significantly reduced by some three to five inches inasmuch asthe containers will be supported directly on the rollers. This allowsthe nested three trash container arrangement, when supported upon thethe rollers of the structural trailer members to meet the heightrestrictions imposed upon highway transportation vehicles, a conditionwhich heretofore could not be achieved when utilizing the usual flatbedtrailer construction to support a nested three container configuration.

The structural main rails of the trailer are supported upon the frontand rear wheels in a manner to normally slope the trailer from front torear to facilitate unloading procedures. The rear end of the trailerrearwardly of the rear wheels is constructed to provide an unloadingramp with a fifteen degree slope. Preferably, the unloading rampterminates approximately fifteen inches above the ground. In thismanner, the trailer can be constructed to provide a self unloadingfeature whereby the angularity of the trailer and the slope of the rearramp can be employed to allow a single driver to self unload the pair ofnested trash containers. In practice, upon reaching the destination, thedriver removes the chains which are employed about the nested containersduring highway transportation procedures. Then, by backing up andsuddenly stopping in successive short stages, the forces of inertia willfunction to cause the pairs of nested containers to roll rearwardlyuntil rearwardmost nest of containers drops free of the trailer. Theprocedure can then be repeated until the forward nest of containersdrops rearwardly of the trailer. A free drop of fifteen inches at therear of the rear unloading ramp has been chosen both to providesufficient rear highway clearance and to assure that the containers willnot be damaged as they fall from the trailer.

In view of the severe height restrictions which are presently in forcein interstate highways, the clearance between the rear wheels of thetrailer and the rearward nest of containers was found to be critical.Because of the load involved, it was found necessary to increase thesize of the rear axle and to increase the size of the rear tires tocarry the load. In view of the criticality of the rear wheel clearance,it was found to be advantageous to block the larger axle to therebysufficiently raise the rear of the trailer. Experiments have proven thata rear wheel clearance of six and one-half inches unloaded and fiveinches when loaded will be satisfactory for transporting six containersin two nested pairs on a single trailer.

In order to achieve the maximum economy and to comply with the sixtyfoot overall length limitation, a trailer having an overall length offorty-five feet has been found to be optimum for the purpose. Theoverall size of the containers when nested in pairs of threes and placedupon the trailer in end-to-end juxtaposition produces an overall loadlength of approximately forty-seven feet, a condition that can bereadily handled on a forty-five foot trailer. As above set forth, thetrailer rear ramp rearwardly slopes to provide fifteen inch rearwardroad clearance. While it has been found that the rearward ramp slope isnot absolutely necessary, it has proved to be beneficial to aid in theself unloading procedures. However, the rearward drop must be minimizedto as great an extent as possible so as not to damage the trashcontainers by the forces of the drop when the nested trash containersare self-unloaded from the trailer. By employing the structuralhoist-type trailer construction and the particular method of nesting andloading the trash containers on the trailer, all of the interstatehighway regulations pertaining to the length, width and height of loadscan be observed, and at the same time, a significantly increased loadcan be carried by substantially the same equipment and personnel thatwas formally utilized.

It is therefore an object of the present invention to provide animproved method and apparatus for transporting roll-off containers ofthe type set forth.

It is another object of the present invention to provide a novel methodand apparatus for transporting roll-off trash containers which includesgenerally a trailer comprising a pair of side by side longitudinal mainrails, inside and outside rollers supported by the rails and a pluralityof six trash containers which are adapted to be supported and carriedupon the trailer in a manner to comply with interstate highway load sizelimitations.

It is another object of the present invention to provide a novel methodand apparatus for transporting trash containers wherein a plurality ofsix roll-off containers are simultaneously carried upon a trailer, thesix containers being subdivided into two sets of nested containerscomprising three containers each.

It is another object of the present invention to provide a novel methodand apparatus for transporting trash containers that includes astructural steel trailer, a plurality of six roll-off containers adoptedfor simultaneous transportation upon the trailer and means to nest thetrash containers relative to each other in two pairs of three containerseach whereby the entire load can comply with interstate highway, height,width and length limitations.

It is another object of the present invention to provide a novel methodand apparatus for transporting roll-off containers which comprises anelongate structural trailer fabricated with a pair of side-by-side mainrails, inside and outside rollers supported upon the rails, means tostack and carry a plurality of six trash containers upon the rails andmeans to unload the trash containers from the trailer at the point ofdelivery without the need to provide any additional unloading equipment.

It is another object of the present invention to provide a novel methodand apparatus for transporting roll-off type trash containers that issimple in design, trouble-free in operation and highly efficient when inuse.

Other objects and a fuller understanding of the invention will be had byreferring to the following description and claims of a preferredembodiment, taken in conjunction with the accompanying drawings, whereinlike reference characters refer to similar parts throughout the severalviews and in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a tractor and trailer fully loadedwith a plurality of six roll-off containers which are stacked in twonests for transportation in accordance with the teachings of the presentinvention.

FIG. 2 is a a side elevational view of the trailer without the load.

FIG. 3 is a top plan view of the trailer showing the nests of containersin phantom lines to illustrate the trash container overhang.

FIG. 4 is an exploded, perspective view showing the arrangement andorientation of three containers prior to nesting.

FIG. 5 is a partially exploded, perspective view of three containersshowing two containers in nested relationship prior to nesting with thethird container.

FIG. 6 is a perspective view showing three containers in fully nestedrelationship prior to shipping.

FIG. 7 is a cross-sectional view taken along line 7--7 on FIG. 3,looking in the direction of the arrows.

FIGS. 8, 9 and 10 are schematic side elevational views showing trashcontainer unloading procedures at the place of delivery.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION

Although specific terms are used in the following description for thesake of clarity, these terms are intended to refer only to theparticular structure of the invention selected for illustration in thedrawings and are not intended to define or limit the scope of theinvention.

Referring now to the drawings, there is illustrated in FIG. 1 a trailer10 which is specially designed and suited for carrying a plurality ofroll-off trash containers 12. The trailer 10 is moved in the usualmanner by a conventional tractor 14 which is suitably connected in amanner well known to those skilled in the art for highway transportationpurposes.

As best seen in FIGS. 2 and 3, the trailer 10 comprises essentially apair of longitudinally extending, transversely spaced structural steelmain rails 16, 18 which rails extend the entire length of the trailer10. A plurality of cross members 20 are formed of suitable structuralsteel shapes and are welded or otherwise connnected between the rails16, 18 to form an extremely sturdy, structurally secure trailerconstruction. In well known manner, the trailer 10 is equipped with aforward king pin 22 for connection to the tractor 14 when the trailer isloaded for trash container transport purposes. Left and right pairs ofrear wheels 24, 26 and 28, 30 are rotatively carried on the transverseaxles 32, 34 in manner well known to those skilled in the trailerconstruction art. In the usual manner, transversely mounted mud flaps 36and front and rear light channels 38, 40 can be provided to comply withany known trailer construction requirements.

As best seen in FIGS. 1 and 2, the main rails 16, 18 terminaterearwardly in a sloped unloading ramp 42, which unloading ramppreferably declines at an angle of fifteen degrees from the planedefined by the tops of the main rails 16, 18. The unloading ramp 42terminates above ground level in a tail board 44 for self unloadingpurposes. The tail board 44 is preferably fabricated of structuralsteel, the same as the remainder of the trailer and can be welded inknown manner to form a sturdy rear end construction. The unloading ramp42 terminates above the road surface or the ground 46 to provide aroll-off container drop that must be sufficient for highway clearanceand at the same time must be minimized so as not to damage the trashcontainers or other transported products, such as compactors, when thetransported equipment is unloaded. A drop of approximately twenty-oneinches has been found suitable for the purpose whereby the transportedcontainers or compactors will not be damaged by a free fall of thismagnitude upon unloading.

As best seen in FIG. 3, the main rails 16, 18 are provided at or neartheir top surfaces 66, 68 with necessary construction components torotatively carry a plurality of inner rollers 52. In known manner, aplurality of outer rollers 54 are also rotatively supported upon thelongitudinally extending rails, 16, 18. It should be noted that the useof both a plurality of inside and outside rollers and the necessaryconstruction components for rotatively carrying the rollers is wellknown in the art and is substantially the standard in the industry forconstruction of hoists. Existing hoist constructions (not shown)utilizing inside and outside rollers are conventionally provided forunloading and loading roll-off trash containers so as to be suitable foruse with containers having bottom rails which are spaced for use witheither inside rollers or outside rollers.

The same general construction has been adopted for the trailer 10 of thepresent invention whereby the trailer can be utilized to load, unloadand transport roll-off trash containers of the type designed for usewith hoists having either inside rollers or outside rollers in the knownmanner. The inside rollers 52 and the outside rollers 54 are rotativelyaffixed to the longitudinal main rails 16, 18 in known manner torotatively receive and support the container bottom rails 80, 82 (FIG.4) to facilitate movement of a trash container 12 longitudinally alongthe main rails 16, 18.

In the preferred construction, the overall length of the trailer 10illustrated in FIGS. 2 and 3 is forty-five feet for carrying two nests56, 58 containing three roll-off containers 64, 84, 86 each. Assumingthat the roll-off trash containers will be a popular size, for example,twenty-two feet in length, then the two nests of containers willforwardly overhang the trailer by approximately one foot and rearwardlyoverhang the trailer by approximately one foot. With approximately twoinches clearance between the container nests 56, 58 there will then be atotal overall trailer length of forty-seven feet, which dimension, whentaken in combination with the free length of the tractor 14, will besufficient to meet the maximum sixty foot overall length legallimitation imposed in many states for interstate highway trucktransportation.

It is noteworthy in FIG. 1 that inasmuch as the bottom rollers 60 of thelowermost trash containers 62, 64 of each nest 56, 58 of containers arenot utilized to support the nests during transportation, the rollerswill be positioned below the respective tops 66, 68 of the main rails16, 18, thereby reducing the overall height of the trash container nests56, 58 as they rest upon the trailer 10. In this manner, when two of theroll-off containers 12 are turned on their side, as illustrated,sufficient height reduction can be achieved by so positioning therollers 60 as not to exceed the interstate highway total heightlimitations.

Referring now to FIGS. 4, 5, 6, and 7, the method of nesting a pluralityof roll-off containers will now be described. As above set forth, eachnest of containers 56, 58 comprises three similar groups consisting of alowermost or support container 62, 64, a middle container 84 and anupper container 86. The nested containers are suitably arranged andsuitably retained to permit six roll-off trash containers 12 to besimultaneously transported in a legal manner upon the trailer 10.Starting with the containers illustrated in FIG. 4, it will be notedthat the hinged rear doors (not illustrated) will first be removed fromassociation with the trash container side walls 70 for properinterfitting purposes. Thus, the side walls 70, 70', 70" respectivelycomprise an integral front wall 72, 72', 72" and rearwardly extendingleft and right side walls 74, 74', 74", 76, 76', 76" respectively. Thefront wall 72, 72', 72" and the left and right side walls 74, 74', 74",75, 76', 76" respectively rise from the container floors 78, 78', 78"and are secured thereto in the usual manner, such as by welding.

As illustrated, the lowermost trash container 62 or 64 is placed uponthe trailer 10 with its bottom rails 80, 82 in rolling engagement uponeither the inner trailer rollers 52 or the outer trailer rollers 54(depending upon the design of the container being shipped) to permitrolling movement of the lowermost trash container relative to thetrailer 10 for unloading and loading purposes. Preferably, the containerfront wall 72 is positioned to overhang the front of the trailer byapproximately one foot. See FIG. 3.

As above set forth, the rollers 60 of the lowermost container 62 or 64extend below the tops 66, 68 of the trailer main rails 16, 18 to therebyreduce the overall height requirements of the system. The rear opening88 which is provided upon removal of the container rear door (not shown)preferably positions to face rearwardly as illustrated. The containers84, 86 are oriented as illustrated in FIG. 4 so that the rear opening88' of the middle container 84 faces in the same direction as theopening 88 of the lowermost container and the rear opening 88" of theupper container 86 is offset through one hundred and eighty degrees.

Next, the other two containers 84, 86 of the nest 56 or 58 are turnedthrough ninety degrees so that the left side 74' of middle container 84faces downwardly and the left side 74" of the other container 86 alsofaces downwardly. The respective rollers 60', 60" of the containers 84,86 are positioned to face in opposite directions as illustrated. Theopen rear 88' of the middle container 84 faces rearwardly and the openrear 88" of the upper container 86 faces forwardly whereby thecontainers 84, 86 may be readily intermeshed by simply urging thecontainers together with the left wall 74" of the container 86 restingupon the left wall 74' of the middle container 84.

As illustrated in FIG. 5, the containers 84, 86 after being positionedon their respective sides can be nested together to form a generallyhollow quadrilateral configuration. The floor 78' of the container 84faces oppositely outwardly away from the floor 78" of the container 86.As best seen in FIG. 6, the pair of side-nested containers 84, 86, whenfully urged to their interlocked position as illustrated in FIG. 5, canthen be lowered into the interior of the lower container 62 or 64 in themanner illustrated. Thus, three roll-off containers 62, 84, 86 or 64,84, 86 can be nested together to require the least volume duringtransportation by providing the minimum overall dimensions for storingthree such containers.

As shown in FIG. 7, the container nests 56, 58 easily ride upon thetrailer 10 for highway transportation purposes without undue widthrequirements. Preferably, once the nests of containers 56, 58 areproperly supported upon the rollers 52 or 54 of the trailer 10, chainsof suitable number and strength (not shown) can be applied about thenested container cargo to prevent shifting during transportion. When theload is safely transported to the point of disposal, the chains can thenbe removed for roll-off container unloading purposes in the mannerhereinafter described.

Referring now to FIGS. 8, 9, and 10, there is illustrated a preferredprocedure for self unloading the nests (56, 58) of containers after thecargo reaches the end of the trip. It will be appreciated that the nests56, 58 could comprise three containers each as illustrated, oroptionally could comprise one container each or two containers each forself unloading purposes.

Starting with the container nests positioned as illustrated in FIG. 8,with the chains (not shown) removed, the driver can slowly back thetrailer 10 by reversing the tractor transmission in known manner. Withthe cargo and trailer slowly moving to the rear, the driver can beinstructed to put his foot upon the brake to suddenly stop the tractor14 and of course the affixed trailer 10. Inasmuch as the cargo of nestedroll-off containers is no longer lashed, chained or otherwise secured tothe trailer 10, the inertia of the containers will function to cause thebottom rails 80, 82 of the lowermost containers 62, 64 to roll over theinner or outer rollers 52, 54 which are provided on the trailer, therebyallowing the container nests 56, 58 to roll rearwardly and in turn downthe sloped unloading ramp 42.

Once a portion of a lowermost container 62 of the nest 56 has come torest upon the ground surface 46 as shown in FIG. 9, the driver can thenplace the tractor motor in a forward gear to slowly move the trailerforwardly. In this manner, the front end of the nest 56 will be causedto roll down the sloped unloading ramp 42 and drop to the ground wherebyboth the front and rear rollers 60 of the lowermost container 62 willthen rest upon the ground surface. The backing, stopping and forwardmovement procedures can be repeated for the front nest 58 to therebyfacilitate complete unloading of the six trash containers by the driverof tractor 14.

Once unloaded, the tractor 14 and the attached trailer 10 can then bereturned to the factory to pick up another load of roll-off containers12. The ultimate user, by employing his existing hoist (not shown) orother equipment can readily unnest the three intermeshed containers foruse in his business in the known manner, at no additional cost to thecontainer manufacturers.

Although the invention has been described with a certain degree ofparticularity, it is understood that the present disclosure has beenmade only by way of example and that numerous changes in the details ofconstruction and the combination and arrangement of parts may beresorted to without departing from the spirit and scope of theinvention.

What is claimed is:
 1. A method for unloading a plurality of at leastfour large containers, each of the type including a floor, a right sidewall, a left side wall, a front wall and at least one bottom railaffixed to the floor from a trailer to the ground by moving the trailer,the trailer being of the type having at least one main rail having a topsurface and a plurality of rollers rotatively secured to the main railcomprising the steps ofpositioning a first portion of at least two ofthe containers upon a forward part of the trailer and supporting abottom rail of only one of the containers on some of the rollers;nesting the first portion of containers prior to moving, the nestcomprising revolving the said container not having its bottom rail onthe rollers and resting a sidewall of the said container upon the floorof the container having its bottom rail supported on the roller;positioning a second portion of at least two of the containers upon arearward part of the trailer and supporting a bottom rail of only one ofthe second portion of the containers upon others of the rollers;rearwardly moving the trailer a short distance and suddenly stopping therearwardly moving trailer; and moving the first and second portions ofthe containers on the rollers relative to the trailer when the rearwardtrailer movement stops, and moving all of the containers off of thetrailer.
 2. The method of claim 1 and the futher step of nesting thesecond portion of the containers prior to moving, the nesting comprisingrevolving the said container not having its bottom rail on the rollersand resting a sidewall of the said container upon the floor of thecontainer having its bottom rail supported on the rollers.
 3. The methodof claim 2 wherein the main rail terminates rearwardly in an unloadingramp that is positioned in spaced relationship above the ground and themoving of the containers comprises dropping separately the first portionof the containers and second portion of the containers through the spacebetween the unloading ramp and the ground.
 4. The method of claim 2wherein the unloading is carried out without additional sxternaldeivices.